1. Field of the Invention
The present invention relates to a key for a keyboard instrument, such as an electronic piano, and more particularly to a key for a keyboard instrument, which is made of a synthetic resin and has a weight attached thereto so as to obtain a desired touch weight to be given during key depression.
2. Description of the Related Art
Conventionally, a key described e.g. in Japanese Laid-Open Patent Publication (Kokai) No. 2009-109601 has been known as the above-mentioned type of key for a keyboard instrument. This key for a keyboard instrument comprises a key body made of a synthetic resin which extends in the front-rear direction and has a rear portion thereof pivotally supported, and a weight attached to the key body. The key body is formed such that a transverse cross section perpendicular to the lengthwise direction has a downwardly open U shape, and a block-shaped weight is bonded to the top, and left and right inner surfaces of the key body, by an adhesive. In this keyboard instrument, the weights are configured to weigh differently according to pitch ranges such that keys for lower-pitched tones are heavier and keys for higher-pitched tones are lighter. Further, in Japanese Laid-Open Patent Publication (Kokai) No. 2009-109601, a method is disclosed in which the key is manufactured by integrally forming the key body and the weight by insert molding such that the weight is built in the key body.
According to the above-described key for a keyboard instrument, in the case of attaching weights to respective key bodies by bonding, it is required to apply the adhesive to the respective surfaces of the weights or the inner surfaces of associated key bodies, and then attach the weights to the respective key bodies one by one. In addition, it is required to cure the adhesive so as to firmly bond the weights to the respective key bodies, which takes time to complete weight attachment. On the other hand, in the case where keys each having a weight therein are manufactured by insert molding, a plurality of types of metal molds are required according to differences in shape and size between the weights. More specifically, in a case where weights are made different in shape and size according to the pitch ranges of keys, a plurality of types of metal molds corresponding to the respective pitch ranges of keys are needed even for the same model of keyboard instrument. As described above, in the case where weights are attached to key bodies by bonding or insert molding, the operation takes much time and labor, which causes an increase in manufacturing costs.